1. Field of the Invention
The present invention relates to an electromagnetic coupling apparatus, such as an electromagnetic clutch for use in controlling the transmission of power from an automobile engine to a refrigerant compressor in an automobile air conditioning system. More particularly, it relates to a connection to a connector in the electromagnetic coupling apparatus.
2. Description of Related Art
In FIG. 1, a known compressor 110 of an automobile air conditioning system is shown. Compressor 110 may include an electromagnetic clutch 109. Electromagnetic clutch 109 may selectively connect and disconnect a drive source to a drive shaft of compressor 110.
Electromagnetic clutch 109 may include an electromagnetic coupling apparatus A. An electromagnetic coupling apparatus A comprises an annular ring case 104, a coil assembly 100, and a connector 103 (shown in FIGS. 2 and 3). Coil assembly 100 is disposed in an annular groove 104b of ring case 104. A bottom portion of ring case 104 is fixed to a housing of compressor 110, via a plate 105.
As shown in FIG. 2, coil assembly 100 includes a coil bobbin 102 and a coil 101 wound around coil bobbin 102. Coil 101 comprises of an electrical wire. Coil 101 has end portions 101a, 110b. An opening 104a is formed through a bottom portion of ring case 104. Coil assembly 100 may be positioned within annular groove 104b of ring case 104, so that end portions 101a, 101b of coil 101 pass through opening 104a. After passing through opening 104a, end portions 101a, 101b of coil 101 may be secured in connector 103. Within connector 103, each of end portions 101a, 101b of coil 101 may be connected electrically with a respective one of a pair of external wires 106a, 106b. Connector 103 may be secured to ring case 104, so that a portion of connector 103 fits into opening 104a of ring case 104.
With reference to FIG. 3, connector 103 includes a hook receiving portions 103a, 103b. By grasping looks 105a, 105b of plate 105 into hook receiving portions 103a, 103b of connector 103, connector 103 may be fixed to the bottom portion of ring case 104.
In the known electromagnetic coupling apparatus A, the plurality of hooks 105a, 105b must engage the plurality of hook receiving portions 103a, 103b by hand. Therefore, the manufacturing efficiency connecting connector 103 to ring case 104 is reduced. If hooks 105a, 105b are engaged to hook portions 103a, 103b, the grasping tool may damage connector 103. Further, in the known electromagnetic coupling apparatus A, the plurality of hooks 105a, 105b are formed in the plate 105, which increases the size of plate 105.
Therefore, a need has arisen for electromagnetic coupling apparatus for use in an electromagnetic clutch that overcome these and other shortcomings of the related art. A technical advantage of the present invention is that grasping portions are not required to connect a connector to a ring case.
In an embodiment of this invention, an electromagnetic coupling apparatus comprises a ring case, a coil and a connector. The ring case comprises an annular groove, which has an open edge. The coil comprises an electrical wire and is disposed in the annular groove of the ring case. An opening is formed through the ring case in its closed end surface. The connector is disposed on the closed end surface of the ring case and covers the opening. Each of a first end and a second end of the coil are connected to one of a pair of lead wires, respectively, of an electric circuit via one of a pair of contacts, respectively in the connector. The connector comprises a housing and a cap. The housing supports the first and the second ends of the coil and the pair of contacts in its interior. The cap closes an end opening of the housing. The coil is covered substantially by an annular resin case. The housing is formed integrally with the annular resin case.
In another embodiment of this invention, an electromagnetic coupling apparatus comprises a ring case, a coil and a connector. The ring case comprises an annular groove, which has an open edge. The coil comprises an electrical wire and is disposed in the annular groove of the ring case. An opening is formed through the ring case in its closed end surface. The connector is disposed on the closed end surface of the ring case and covers the opening. Each of a first end and a second end of the coil are connected to one of a pair of lead wires, respectively, of an electric circuit via one of a pair of contacts, respectively in the connector. The connector comprises a housing and a cap. The housing supports the first and the second ends of the coil and the pair of contacts in its interior. The cap closes an end opening of the housing. A resin annularly encases the entire the coil. The housing is formed integrally with the annular resin mold.
In still another embodiment of this invention, an electromagnetic coupling apparatus comprises a ring case, a coil and a connector. The ring case comprises an annular groove, which has an open edge. The coil comprises an electrical wire and is disposed in the annular groove of the ring case. An opening is formed through the ring case in its closed end surface. The connector is disposed on the closed end surface of the ring case and covers the opening. Each of a first end and a second end of the coil are connected to one of a pair of lead wires, respectively, of an electric circuit via one of a pair of contacts, respectively in the connector. The connector comprises a housing and a cap. The housing supports the first and the second ends of the coil and the pair of contacts in its interior. The cap closes an end opening of the housing. The coil is covered substantially by an annular resin case. The housing is glued on an end surface of the annular resin case that is disposed to correspond to the opening of the ring case.
In yet another embodiment of this invention, an electromagnetic coupling apparatus comprises a ring case, a coil and a connector. The ring case comprises an annular groove, which has an open edge. The coil comprises an electrical wire and is disposed in the annular groove of the ring case. An opening is formed through the ring case in its closed end surface. The connector is disposed on the closed end surface of the ring case and covers the opening. Each of a first end and a second end of the coil are connected to one of a pair of lead wires, respectively, of an electric circuit via one of a pair of contacts, respectively in the connector. The connector comprises a housing and a cap. The housing supports the first and the second ends of the coil and the pair of contacts in its interior. The cap closes an end opening of the housing. A resin annularly encases the entire the coil. The housing is glued on an end surface of the annular resin case that is disposed to correspond to the opening of the ring case.
In a further embodiment, the invention comprises a method for assembling an electromagnetic coupling apparatus. The method comprises the steps of: encasing a coil covered substantially by an annular resin encasement, e.g., an annular resin case or an annular resin mold, in a ring case, and positioning a housing of a connector, which is formed integrally with the annular resin encasement, in an opening of the ring case. This method further comprises the steps of connecting a plurality of contacts with a pair of lead wires and with a plurality of support portions of the housing; and closing an end opening of the housing by a cap of the connector. In this method, the encasing step and the positioning step may be performed simultaneously.
Other objects, features, and advantages of embodiments of this invention will be apparent to, and understood by, persons of ordinary skill in the art from the following description of preferred embodiments with reference to the accompanying drawings.